Air Pollution
Atmosphere need to know:
– Air is more dense at sea level
– 75-80% of air mass found in troposphere
– Atmosphere contains 78% N, 21%O, and 1% trace
gases like, methane, nitrous oxide, ozone, argon,
water vapor, and carbon dioxide. Also soot, and
dust.
– Ozone (3 O2 + UV
2 O3) blocks 95% UV
– Ozone keeps O from forming photochemical
ozone, a harmful pollutant near the ground
Air Pollution
• What is Air Pollution?
– the presence of chemicals in the atmosphere at
concentrations high enough to harm organisms,
ecosystems, and human made items.
• Effects range from annoying to lethal.
• Natural sources include dust, smoke, and VOC’s
released by certain plants. Most are spread out or
removed by chemical cycles, precipitation, and gravity.
• Human inputs of air pollution are mostly due to
industry, transportation, and densely populated areas.
Air Pollution
(a glance through time)
• Humans burning wood in poorly ventilated space.
• Middle ages haze of wood smoke around urban areas.
• Industrial Revolution required burning coal which led to great
increases in respiratory diseases.
• Late 1800’s saw people in London dying from the “pea soup” fogs
caused by dense coal smoke mixtures.
• 1952 a yellow fog killed approximately 4000-12000 Londoners.
British Parliament passes Clean Air Act of 1956.
• US in the 1940’s experienced severe air pollution.
• Donora, Pennsylvania experienced first air pollution disaster in
October 1948. A 5 day toxic fog sickened 6,000 people and killed 20.
• New York City 1963: 300 people die and thousands more sickened.
• US develops the Clean Air Act of 1970
Air Pollution
• Primary Pollutants – harmful chemicals
emitted directly into the air from natural
processes and human
• Secondary Pollutants – formed when primary
pollutants react with one another or with
basic components of air to form new harmful
Air Pollution
Air Pollution
Urban vs. Rural?
What about the wind?
Developed vs. Developing countries?
• 1.1 billion people live in urban areas where outdoor air
is unhealthy. (WHO)
• Developing Countries do not have Air Pollution Laws.
• Indoor air pollution is major problem for the poor
• Air Pollution is no longer a regional problem it is a
global problem.
Major Outdoor Air Pollutants
Carbon Oxides – CO, CO2; form during the incomplete
combustion of carbon containing materials.
Ex.(motor vehicle exhaust, tobacco smoke, open fires,
inefficient stoves, and forest and grassland fires.
• CO reacts with hemoglobin in red blood cells and
reduces the ability of blood to transport oxygen
throughout the body.
• 93% of CO2 results from the carbon cycle, the rest
comes from human activities such as deforestation and
burning of fossil fuels.
• CO2 levels have been on the rise since the industrial
revolution and documented well since the 1950’s.
Major Outdoor Air Pollutants
Nitrogen Oxides and Nitric Acid - NO, HNO3; nitrogen and oxygen gas
react at high combustion temperatures in automobile engines and
coal-burning plants. Lighting and certain bacteria also produce NO.
• NO2 reacts with water vapor to create HNO3 and nitrate salts (NO3-)
which cause harmful acid deposition.
• Both NO and NO2 play a role in forming photochemical smog.
• Nitrous oxide (N2O) a greenhouse gas is emitted from fertilizers,
and animal wastes and is produced by burning fossil fuels.
• Nitrogen Oxides can irritate the eyes, nose, and throat; aggravate
lung ailments and increase susceptibility to respiratory infections.
• Nitrogen Oxides can also suppress plant growth and reduce visibility
when they are converted to nitric acid and nitrate salts
Major Outdoor Pollutants
Sulfur dioxide and sulfuric acid – SO2, H2SO4; about 1/3 of
SO2 in the atmosphere comes from natural sources. The other
2/3 come from human sources, mostly from burning sulfur
containing coal, oil refining and smelting of sulfide ores.
• SO2 can be converted to aerosols of H2SO4 and suspended
particles of sulfate (SO42-) salts which lead to acid
deposition.
• Sulfur dioxide, sulfuric acid droplets, and sulfate particles
reduce visibility and aggravate breathing problems. SO2 and
H2SO4 can damage crops, trees, soils, and aquatic life in
lakes. They also corrode metals and damage paint, paper,
leather, and stone on buildings and statues.
Major Outdoor Air Pollutants
Particulates(Suspended Particulate Matter) SPM; Consists
of a variety of solid particles and liquid droplets that can
remain suspended in the air for long periods of time.
• 62% of SPM exists from natural sources, dust, smoke,
sea salt. 38% exists comes from human sources, coal
burning power plants, motor vehicles, plowed fields,
road construction, unpaved roads, and tobacco smoke.
• Since 1990 more than 2000 studies link SPM to adverse
health affects.
• According to the EPA and Harvard School of Public
Health, particulate air pollution is responsible for
60,000-70,000 premature deaths a year.
Major Outdoor Air Pollution
Particulates Continued. . .
• The most harmful forms of SPM are fine particles ( average
diameter of less than 10 micrometers) and ultra fine
particles (average diameter of 2.5 micrometers).
• These particles can irritate the nose, throat, damage lungs,
aggravate asthma and bronchitis, and shorten life.
• Toxic particulates such as lead, cadmium, and PCB’s
(polychlorinated biphenyls) can cause mutations,
reproductive problems, and cancer.
• Particulates also reduce visibility, corrode metals, and
discolor clothes and paints.
Major Outdoor Air Pollution
Ozone – O3; a major component of photochemical
smog. Ozone found in the troposphere is
considered “bad” ozone, while stratospheric ozone
is considered “good” ozone.
• Ozone can cause coughing and breathing
problems, aggravate lung and heart disease,
reduce resistance to colds and pneumonia,
irritate eyes, nose, and throat.
• Ozone also damages plants, rubber in tires,
fabrics, and paints.
Major Outdoor Air Pollutants
Volatile Organic Compounds (VOC’s); Organic
compounds that exist as gases in the atmosphere. Most
are hydrocarbons such as isoprene and terpenes, emitted
by plants, and methane which is a greenhouse gas.
• 1/3 of methane comes from natural sources such as
plants, wetlands, and termites. The rest come from
human sources primarily rice paddies, landfills, oil and
natural gas wells, and cows.
• Other VOC’s including benzene, vinyl chloride, and
trichloroethylene (TCE) are used as industrial solvents,
dry cleaning fluids, and components of gasoline,
plastics, drugs, synthetic rubber, and other products.
Major Outdoor Air Pollutants
Volatile Organic Compounds continued. . .
• Benzene is found in motor vehicle and power
plant emissions, and tobacco smoke.
• Long term exposure can lead to leukemia,
numerous blood disorders, and immune
system damage.
• Short term exposure to high levels can cause
dizziness, unconsciousness, and death.
Major Outdoor Air Pollution
Lead (Pb); since it is a chemical element lead does
not break down in the environment.
• Lead is a potent neurotoxin and can damage the
nervous system. Each year 12,000-16,000
American children under age 9 are treated for
acute lead poisoning. About 200 die. 30% of
survivors suffer from palsy, partial paralysis,
blindness and mental retardation.
• Children under 6 and unborn fetuses are
especially vulnerable to lead exposure
Major Outdoor Air Pollution
Lead continued. . .
• Between 1976 and 2000, the percentage of US children
ages 1-5 with blood lead levels above the safety standard
dropped from 85% to 2.2%
Why?
• The US banned the use of leaded gasoline and lead based
paint in 1976 to have a complete phase out by 1986.
• US centers of Disease Control estimate that at least
310,000 children still have unsafe blood levels of lead
caused by exposure to lead based paint found in
approximately 38 million homes built before 1960, and lead
contaminated dust in deteriorating buildings.
Major Outdoor Air Pollution
Lead continued. . .
• Lead has been found in lipsticks, toys, and can
leach from water pipes and faucets.
• Developing countries still battling with high
lead poisoning issues, predominately due to
the use of leaded gasoline.
Major Outdoor Air Pollution
Lead (Pb) Poisoning
Prevention
Control
• Phase out lead gasoline
worldwide
• Phase out Waste incineration
• Ban use of lead solder
• Ban use of lead in computer
and TV monitors
• Ban lead glazing for ceramic
ware used to serve food
• Ban candles with lead cores
• Test blood for lead by age 1
• Replace lead pipes and plumbing
fixtures containing lead solder
• Remove leaded paint and lead
dust from older homes and
apartments
• Sharply reduce lead emissions
from incinerators
• Remove lead from TV sets and
Computer monitors before
incineration or land disposal
• Test for lead in existing ceramic
ware used to serve food
• Test existing candles for lead
• Wash fresh fruits and vegetables
Industrial Smog
Ammonium sulfate (NH4)2SO4
Ammonium sulfate salts and soot are
what cause smog to appear gray in
color. Therefore it is sometimes called
gray air smog.
Ammonia (NH3)
Sulfuric acid (H2SO4)
Water Vapor (H2O)
Sulfur trioxide (SO3)
Oxygen (O2)
Sulfur dioxide (SO2)
Sulfur in coal and oil
Carbon Monoxide (CO)
and
Carbon dioxide (CO2)
Burning Coal and oil
Mixing with oxygen (O2)
Carbon in coal and oil
Photochemical Smog
PAN’s and other pollutants
Photochemical smog exists in all
modern cities. NO2, O3, and PAN’s are
considered to be Photochemical
oxidants. Hotter days lead to high
levels of ozone and photochemical
smog.
VOC’s
Ozone (O3)
O2
Nitric Oxide + Oxygen
H2O and UV radiation
Nitrogen dioxide (NO2)
O2
Nitric oxide (NO)
O2
Nitrogen (N) in fossil fuel
Peroxyacyl nitrates (PAN’s)
Hydrocarbons
Factors for increasing or decreasing
Air Pollution
Decreasing
Increasing
• Particles heavier than air settle
out.
• Rain and snow cleanse the air.
• Salty sea spray wash out
particles and water-soluble
pollutants as air flows from
land to sea.
• Winds sweep pollutants
diluting them.
• Natural chemical reactions
remove pollutants. Acid
Deposition.
• Urban buildings can slow wind.
• Hills and mountains can reduce
air flow.
• High temperatures promote
chemical reactions.
• VOC’s from plants and trees in
wooded urban areas can play
major role in photochemical
smog formation.
• Grasshopper effect – air
pollutants from the tropics make
their way to the Arctic
• Temperature Inversions trap
pollutants
Acid Deposition
Acid Deposition
• Can be wet or dry.
• Has been occurring since the industrial revolution.
• Is a regional air problem for areas downwind of coal-burning
facilities and urban areas with many motor vehicles.
• Is neutralized by Limestone soils that buffer the acid affect.
• Harms thin acidic soils which provide no such buffering.
• Leaches toxic metals (Pb and Hg) into lakes and water sources,
which can bioaccumulate in fish, mammals, and birds.
• Lowers pH of aquatic ecosystems harming fish. (pH < 4.5)
• Harms crops by lowering soil pH
• Effects Forests by leaching calcium and magnesium from the soils
and allowing other metals such as Al, Cd, Hg, and Pb which weaken
trees.
Acid Deposition
Acid Deposition
Acid Deposition
Prevention
• Reduce coal use
• Burn low sulfur coal
• Increase use of renewable
energy resources
• Remove SO2 particles and NOx
from smokestack gases
• Remove NOx from motor
vehicular exhaust
• Tax emissions of SO2
• Reduce air pollution by
improving energy efficiency
Cleanup
• Add time to neutralize
acidified Lakes
• Add phosphate fertilizer to
neutralize acidified lakes
Indoor Air Pollution
• The most threatening indoor air pollutants are smoke and soot
from wood and coal cooking fires, and chemicals used in building
materials and products.
• Poses a much greater threat to human health than outdoor
pollution.
• Since 1990 EPA has placed indoor air pollution at the top of the list
for 18 sources of cancer risk.
• Particulates such as pollen, pet dander, dust mites, and cooking
smoke particles can irritate lungs, cause asthma attacks, itchy eyes,
runny nose and lung disease.
• Toxic airborne spores of molds and mildew can cause headaches
and allergic reactions. They can aggravate asthma, and other
respiratory diseases.
• Sick Building Syndrome effects 1 in 5 commercial buildings in the
U.S.
Indoor Air Pollution
• Four most dangerous indoor air pollutants in developed
countries are tobacco smoke, formaldehyde, radioactive
radon-222 gas, and very small particles.
• Exposure to formaldehyde can lead to an increase risk of
Lou Gehrig's Disease (ALS).
• In 2008 CDC measured unhealthy levels of indoor levels of
formaldehyde in many of the trailers and mobile homes
used for Hurricane Katrina victims.
• Radon-222 is produced by the natural radioactive decay of
Uranium-238. Can accumulate in buildings where it decays
to Polonium-210 and can cause lung cancer.
• Smokers and former smokers tend to be the most
susceptible to radon-related lung cancers. (90%)
Air Pollution Laws and Regulations
• Clean Air Acts 1970, 1977, 1990
• National Ambient Air Quality Standards
– CO NOx SO2 SPM O3 Pb
– Primary Standard to protect human health
– Secondary Standard prevent environmental and property
damage
• Emission Standards
– Hazardous Air Pollutants (HAP’s) that cause health and
ecological effects.
– Toxic Release Inventory (TRI) requires 21,500 refineries, power
plants, hard rock mines, chemical manufactures, and factories to
report their releases and waste management methods for 667
toxic chemicals.
Air Pollution Laws and Regulations
Environmental Scientists applaud the success of U.S. air pollution control laws
but point to the following deficiencies:
• The US continues to depend on pollution cleanup rather than prevention.
• US congress failed to increase fuel-efficiency standards for cars, SUV’s, and
light trucks.
• Regulations of emissions from motorcycles and two cycle gasoline engines
remain inadequate.
• There is little to no regulation of air pollution from oceangoing ships in
American ports.
• Airports are exempt from many air pollution regulations.
• Laws do not regulate emissions of greenhouse gas CO2.
• Ultrafine particles are not regulated.
• Urban ozone levels are still too high in many areas.
• The laws have failed to deal seriously with indoor air pollution.
• There is need for better enforcement of the Clean Air Acts.
Emissions Trading /Cap and Trade
• Producers of air pollutants can buy and sell
pollution rights.
• Proponents argue it is cheaper than government
management.
• Critics say it allows older facilities to shirk their
environmental responsibilities to reduce their
pollution.
• System tends to move pollutants to other areas
without any real reduction in air pollution.
• What about mercury?
Stationary Source Air Pollution
Solutions
Prevention
• Burn low-sulfur coal
• Remove sulfur from coal
• Convert coal to a liquid or
gaseous fuel
• Shift to less polluting energy
sources
Dispersion or cleanup
• Disperse emissions above
thermal inversion layer with
tall smokestacks.
• Remove pollutants after
combustion.
• Tax each unit of Pollution
produced
Motor Vehicle Air Pollution
Solutions
Prevention
• Use Mass Transit.
• Walk or Bike.
• Use less polluting fuel.
• Improve fuel efficiency.
• Get older polluting cars off
the road.
• Give large tax write-offs or
rebates for buying lowpolluting, energy efficient
vehicles
Cleanup
• Require emission control
devices.
• Inspect car exhaust systems
twice a year.
• Set strict emission
standards
Indoor Air Pollution
Solutions
Prevention
Cleanup or dilution
• Clean ceiling tiles and line AC
ducts to prevent release of
mineral fibers.
• Ban smoking or limit it to wellventilated areas.
• Set stricter formaldehyde
emissions standard for carpet,
furniture, and building materials.
• Prevent radon infiltration.
• Use office machines in well
ventilated areas.
• Use less polluting substitutes for
harmful cleaning agents, paints,
and other products.
• Use adjustable fresh air vents
for work spaces.
• Increase intake of outside air.
• Change air more frequently.
• Circulate a building’s air
through rooftop greenhouses.
• Use efficient venting systems
for wood-burning stoves.
• Use exhaust hoods for stoves
and appliances burning natural
gas.
Air Pollution
Solutions
Prevention
• Improve energy efficiency
to reduce fossil fuel use.
• Rely more on lowerpolluting natural gas.
• Rely more on renewable
energy.
• Transfer energy efficiency,
renewable energy, and
pollution prevention
technologies to developing
countries.
Cleanup or Dilution
• Reduce Poverty.
• Distribute cheap and
efficient cookstoves or solar
cookers to poor families in
developing countries.
• Reduce or ban indoor
smoking.
• Develop simple and cheap
tests for indoor pollutants
such as particulates, radon,
and formaldehyde.
What can you Do?
Indoor air Pollution
• Test for radon and formaldehyde inside your home and take
corrective measures as needed.
• Do not buy furniture and other products containing formaldehyde.
• Remove your shoes before entering your house to reduce inputs of
dust, lead, and pesticides.
• Test your house or workplace for asbestos fiber levels, and check
for any crumbling asbestos materials if it was built before 1980.
• Do not store gasoline, solvents, or other volatile hazardous
chemicals inside a home or attached garage.
• If you smoke, do it outside or in a closed room vented to the
outside.
• Make sure that wood burning stoves, fireplaces, and kerosene/gas
burning heaters are properly installed, vented, and maintained.
• Install carbon monoxide detectors in all sleeping areas.